mobile-nixos/overlay/mruby-builder/mrbgems/mruby-lvgui/lvgui.nix

{ stdenv
, pkgs
, lib
, fetchFromGitHub
, pkg-config
, SDL2
, withSimulator ? false
}:

let
  inherit (lib) optional optionals optionalString;
  simulatorDeps = [
    SDL2
  ];

  # Allow libevdev to cross-compile.
  libevdev = (pkgs.libevdev.override({
    python3 = null;
  })).overrideAttrs({nativeBuildsInputs ? [], ...}: {
    nativeBuildInputs = nativeBuildsInputs ++ [
      pkgs.buildPackages.python3
    ];
  });
in
  stdenv.mkDerivation {
    pname = "mobile-nixos-early-boot-gui";
    version = "2020-02-05";

    src = fetchFromGitHub {
      fetchSubmodules = true;
      repo = "lvgui";
      owner = "mobile-nixos";
      rev = "a3412d9e2a8d1c7a23b48cf2cdf2c39cf4009651";
      sha256 = "1ibdjnqjacw27wmdg1fir4isffq2v87ml382f4g76ldmi5za0n9l";
    };

    # Document `LVGL_ENV_SIMULATOR` in the built headers.
    # This allows the mrbgem to know about it.
    # (In reality this should be part of a ./configure step or something similar.)
    postPatch = ''
      sed -i"" '/^#define LV_CONF_H/a #define LVGL_ENV_SIMULATOR ${if withSimulator then "1" else "0"}' lv_conf.h
    '';

    nativeBuildInputs = [
      pkg-config
    ];

    buildInputs = [
      libevdev
    ]
    ++ optionals withSimulator simulatorDeps
    ;

    NIX_CFLAGS_COMPILE = [
      "-DX_DISPLAY_MISSING"
    ];

    makeFlags = [
    ]
    ++ optional withSimulator "LVGL_ENV_SIMULATOR=1"
    ++ optional (!withSimulator) "LVGL_ENV_SIMULATOR=0"
    ;

    # TODO: `make install`...
    installPhase = ''
      mkdir -p $out/lib
      cp -vr lib*.a $out/lib/

      mkdir -p $out/include
      find . -name '*.h' -exec install -vD '{}' $out/include/'{}' ';'

      mkdir -p $out/lib/pkgconfig
      cat <<EOF > $out/lib/pkgconfig/lvgui.pc
      Name: lvgui
      Description: LVGL-based GUI library
      Version: $version
      Requires: ${optionalString withSimulator "sdl2"} ${optionalString (!withSimulator) "libevdev"}

      Cflags: -I$out/include
      Libs: $out/lib/liblvgui.a
      EOF
    '';

    enableParallelBuilding = true;
  }